1. Field of the Invention
The present invention relates generally to eyewear, and more particularly, to an improved system for coupling lens to an eyeglasses frame.
2. Description of Related Art
Eyeglasses for a number of different applications have been provided in the prior art. Typically, eyeglasses are provided with lens that serve a purpose, such as correcting a wearer's vision, filtering sunlight, or preventing airborne objects from impacting the wearer's eyes. Often the lens may serve more than one of these functions, such as both filtering sunlight and providing impact protection, for example.
In some instances, it may be desirable to change the lens in a frame of the eyeglasses. During sports activities for example, while impact protection is a constant desirous feature, it may be necessary to increase or decrease the tint of the lens, to compensate for different sunlight conditions. Another example would be where the lens needs replacement, due to a changing prescription in the case of corrective lenses, or damage to an impact resistant lens. In these situations, the eyeglass frame is often in good condition and only the lens needs to be replaced. However, since the lens is permanently affixed to the frame, the entire eyeglass is replaced. This becomes somewhat expensive for the consumer and may prevent them from obtaining new lenses when it is necessary.
An example of eyeglasses that embody a detachable lens is disclosed in U.S. Pat. No. 4,730,915, to Jannard. The disclosed sunglasses include a unitary transparent lens that extends in a plane that is preferably precisely cylindrical in as-molded condition. The lens has one or more tangs integral with the pane that project over notched areas, that extend inwardly of rearwardly extending lateral terminals. The sunglasses are also provided with a top frame that consist of relatively rigid molded plastic. The top frame has a slot formed upwardly therein with a shallow recess at each end of the slot. The slot has a curvature slightly different than the pane, to provide a mismatch for gripping the pane. The tangs extend in the shallow recesses, to help retain the pane in the top frame.
A disadvantage of the disclosed sunglasses is that it is not suited for glasses having two lenses. The combination of the mismatch between the slot's curvature and the curvature of the unitary pane, and the further combination of the tangs extending into the recesses, all interact to retain the pane in the top frame. With eyeglasses having two lenses, where the lens do not extend the length of the slot and where the curvature of the lens is not different from the curvature of the frame, the disclosed sunglasses would not retain the lenses in the frame. A further disadvantage of the disclosed sunglasses is that over time the pane and frame may lose some of their resiliency. As the pane loses it's resiliency, the frame becomes brittle and the tangs may break off of the frame, when removing or inserting panes in the slot. Without the tangs, the pane can no longer be securely coupled to the top frame.
U.S. Pat. No. 4,674,851, to Jannard, is directed to removable multi-component sunglasses. The disclosed pane and top frame are substantially the pane and top frame as disclosed in U.S. Pat. No. 4,730,915. However, U.S. Pat. No. 4,674,851 does not include a pane that includes tangs, such as those disclosed in subsequent U.S. Pat. No. 4,730,915. Apparently, the pane of the '851 patent was somewhat prone to inadvertently detaching from the top frame, which necessitated the use of tangs as disclosed in U.S. Pat. No. 4,730,915.
Thus, there exists a need for an improved system for coupling one or more lens to an eyeglasses frame.